Sleep apnea is a growing medical problem estimated to affect up to 18 million Americans. People who have the condition—which comes from the Greek word meaning “want of breath”—stop breathing for periods of 10 or more seconds while sleeping

Obstructive sleep apnea—and the form discussed in most detail in this article—is much more common and occurs when the muscles of the throat relax, thus obstructing the free flow of air in and out of the nose and/or mouth. Obstructive sleep apnea can result from many causes, including being overweight, defects in the airway such as enlarged tonsils or adenoids, an unusually narrow throat, and other factors. Men are affected by the condition more often than women, and most cases are diagnosed in those over age 40 (although children can suffer from sleep apnea as well).

Central sleep apnea occurs when the brain fails to send the appropriate signals to the muscles that control breathing. This form of the condition is rare in otherwise healthy people, usually occurring only in people who are ill with other conditions like heart failure. But can be seen in patients with a history of stroke, brain injury as the brain controls breathing. Central apnea can also be seen in patients who use narcotics on a regular basis.

The third form of sleep apnea is known as mixed sleep apnea and is a combination of the other two forms.

In sleep apnea, the brain detects the absence of breath via a drop in oxygen and rise in carbon dioxide and arouses the individual so breathing can continue. Normal breathing is quickly resumed and the person falls back asleep, often not even realizing the arousal has occurred. But because these arousals can occur many times each night—100 or more per hour—the result is an interrupted night's sleep which leads to daytime sleepiness and other problems. Recent studies have linked sleep apnea to high blood pressure, diabetes, irregular heartbeat, and heart attacks and stroke. People with sleep apnea are also three times more likely to be involved in a motor vehicle accident, and reports have suggested they suffer disproportionately from depression, sexual dysfunction, irritability, and memory problems and learning difficulties.

Reviewed: March 18, 2005
Updated: March 22, 2005